Final answer:
In the event of observing a buoy off station, the appropriate action is to immediately contact the nearest Coast Guard office by radiophone to ensure maritime safety.
Step-by-step explanation:
If you observe a buoy off station, you should immediately contact the nearest Coast Guard office by radiophone. This is because buoys are critical aids to navigation, and if they are not in their correct positions, they can pose a significant hazard to navigation. The Coast Guard is responsible for maintaining these aids to navigation and relies on the observations of mariners to ensure their accuracy and reliability. When you contact them, provide all relevant details, such as the buoy's intended position, its current location, and any identifying markings.